Sterilizing water heater



March 31, 1953 H. D. sTERlcK STERILIZING WATER HEATER Filed Oct. 4, 1950 INVENTOR. HHREJSOA/ .QJrAPJcK. BY M TOPA/E Ks:

Patented Mar. 31, 1953 p UNITED- STATES PATENT OFFICE STERILIZI-NG WATER: HEATER?! Harrison D; Sterick, Pittsburgh' laa Application October 4, 1950', seria1Nc: ss;299

1 to apparatus for heating. households,v

Thisinvention-relates and sterilizing water foruse inrestaurants; hospital's, etc.

,A-n 'object of the invention is to prcvid-e -an' efficient device" foruniformly and continuously heating a suppl of water passing through it.-

Another object is to bring" all" of the water which passes through theheater to a" sterilizing temperature (e.- g: about 180")", whichis ordinarily higher than" the temperature desired (-e-.' g. 140) for use-- in bathing, washing thehands, washing clothes and-*dishes, etc:

Another objectis t'o-heat'" all the water'passing through the heater t'oa' high temperature "for sterilization and thereafter: to cool itdown to a lowerydesired temperature for use by having it pass in 'heat transferrelatiorr to the cold water" coming into-thedevice. This-conserves: fuel and makes for a more e'fiicient' continuous operation.

Another "object is to reduce'or 'pr'event precipitationof water on the coils exposed "to water on the inside and gas under combustion on the outside.

By'themeans described" the" water is reduced from the undesirablyhi'gh sterilizing temperature to" the desiredtemperature for ordinary uses while at the same time preheating and raising the temperature of-the coldwater comingj into the system, Therefore a minimum loss of heat unitsresultsfrom the intentional cooling of the previously-heated and 'sterilizedlwater'.

Doctors" now believe'tha't many diseases result.

or may result from drinking unsteri'lized water or washing food-serving dishes and" the like in waterthatcontainsliving germs or bacteria. The conventional hot water heaters may raise the-"water to sterilizing" temperature, but when it is'us'ed at thev high tem erature of exit from suchi'heaters it is usually cooled down/by the addition of and mixing with cold water, which ordinarilyjhas not been sterilized. Consequently,

the resultant. hot water. may be contaminated;

even though part of. it has been sterilized, by'the.

"addition of water which. has not been. heat treated'. V

'Referring. tothe drawings. Fig. 1. is a central vertical sectional view through. the preferred form of. my device; Figs. 2,3 andu l are similar views of'mod'ified forms, with. the outer. shell removed. g

7 Referring. to Fig. 1,.Ithe device comprises an outershell I' whichjmay be either square incrosssection. or of cylindrical shape. Shown at the left lower portionv of. Fig. 1, are two concentric pip'esZ .and 3, broken awayat. their exposed ends.

Cold water suppliedto the heatingand sterilizing device of Fig. I enters. the small inlet pipe 2, and after ithas passed upward through and. been heated in. theldevice may be discharged into the unper' end of the larger outletpipe 3-,. which 6 Claim st (Cl. 122-250);

surrounds the primary-heateexchang:portion of t jmettpipg; A; ggsi ne z=. B 'ofliconventi'onal type is connected to any suitablesource of: gasby the pipe 5.- Aqconventibnal' 'pilot lie ht li ia provided a: conventional thermostat safety control element; 1 close:- byy'for shutting. oifiithe. gas and the pilot light ifthe bumenand; pilot" should be extinguished;

This pilot light' and automatic! thermostat) ,1 safety control areconventional in construction andfunction and-need'not be' described irrdetail: The whole thermostatic'control arrangement; of

the gas supply is indicatedass 'lli The f-unctioniing a and construction on such. controls. are Jwell known and per se form no' part of this inventiom Theconventional thermostat fuel controlele v ment 8 is positionedin the mid-dletportion: ofi the device and extends into theihot water nearits hottestpoint. A suitable graduated. dial may be provided for adjusting-"this" thermostat assembly T 80 that thegas fiowmay be controlledeto pro duce and maintain any desired temperature (be low 200 F.)- for the water at -the-place wherethe thermostat is inserted Thecontraction and exst pansion of element--8 controls the supply of gastothe burner in; well-known manner;

Gas from the burner is ignited and consumed. in the chamber above the hurner; Awire mesh inside thecasing D; This helix formed .by the pipe. 22) is preferablyprovided with heat absorbing fins F so that maximum heating ofIthe-water is obtained in'this secondary helical... rtion of the inlet pipe. The water will be at'its hottest point at thelower outlet end of'the helical pipe 2b, and at this point will have been raised to" or above sterilizing temperature:- It maybe drawn. on for use as very hot'water at this stagethrough" the valve 15, orit maybe returned throughthe draw-01f pipe 3" which surroundsand incloses the primary helicalportion of the pipe 2, as previously described". v

The primary portion jof. the (inlet pipe 2}, with; its surrounding larger outlet pi'pel 3,v and the direct heating. secondary helical. portion of the. pipe 2?) areshown as spaoedf apart. upon acommon vertical axis. The term axis isref'erredfto herein as locating the several. helical coil'st ot aesaios open space between the pipes, the walls of the pipes having a common centre when viewed at any given cross-section through the two pipes.

This arrangement provides for preheating the cold water as it comes into and passes upwardly in the primary helix by contact with and absorption of heat from the surrounding outlet helical pipe. The secondary helix, connected to and above the primary inlet pipe, is directly exposed to the heat of the combustion chamber, and raises the water to the desired sterilizing temperature. It is thereafter progressively reduced to normally usable temperature by heat exchange with the primary portion of the inlet pipe while water is drawn off through pipe 3.

. An exhaust opening ill is provided through the top of outer shell I and through the top of casing D so that spent gases may be drawn on through a suitable flue connection ii.

Near the top of the main casing C the upper portion of the larger outer pipe 3 is provided with a supplemental draw-01f extension it having an intermediate valve 15. Near this outlet M the inlet pipe 2 passes through the outer pipe 3 by means of any conventional arrangement, e. g. the L.-union it. The inlet pipe 2 has an upward extension 2a, which leads to the top of the smaller casing D, and then connects to finned secondary portion 2b inside casing D, which is wound spirally downward in the casing D. Detachable union l8 and T-union 2!! connect secondary portion 2b to. the main outer return hot Water outlet pipe 3.

The mesh screen S used to line the casings C and D is positioned outside the coiled watercarrying pipes. .It tends to reduce radiation of heat to the casing, and in effect acts as a refiector of radiatedfheat, thereby conserving the heat caused by combustion of gas in the main chamber. It may be made either of woven wire like that used ,ina screen door, or of expanded metal. Woven wire is shown.

The operation of the device shown in Fig. 1 is as follows: a valve (not shown) in the pipe 3 extending from the left lower portion of the casing, is opened and hot water flows through the valve to any desired point of use. At the same. time cold water flows into the system through constantly open pipe 2 at the same rate that hot water is drawn off by pipe 3. The cold water in pipe 2 passes upward through the primary helical coil 2 inside casing C. The incoming cold water in the primary heat-exchange portion of inlet pipe 2 is thus surrounded by the outlet pipe 3 which is filled with outgoing hot water. The cold water in that portion of pipe 2 is partially preheated by the hot water in the surrounding pipe 3 and at the same time the hot water in the outlet pipe is cooled down to a desired lower temperatureby the cold water in the. inner inlet pipe.

The cold water in the inlet pipe when it leaves the primary heat-exchange portion passes upward through extension pipe 2a and then through the downwardly coiled secondary directly heated portion shown as finned pipe 2b in the supplementary casing D where it absorbs heat rapidly from the hot exhaust gases, flowing back into the main outlet pipe 3through the T-union 29. From that time on the water which has now reached a high degree of temperature (e. g. 180) passes downward through the large outlet pipe 3, to be discharged as shown in the lower left portion of the, figure.

If it is desired to draw off the hottest water, that may be done by opening the supplemental draw-on" valve l5 in extension I positioned at the top of outlet pipe 3, thus permitting the water at its hottest stage to be drawn off through pipe l4. However, the valve i5 is normally closed. By control of fuel by means of the thermostat, water at the top of pipe 3, at the point where the thermostat is located, is heated to any desired temperature short of boiling, and thereafter is cooled down to the desirable usable temperature by passing around the incoming cold water pipe, as above described.

Fig. 2 shows a modification. The screen S and outer shell I are not shown. Their use is preferred but not always necessary. The cold water passes in through the small inlet pipe 22 just above the burner. The cold water inlet pipe is surrounded and inclosed by the larger hot water outlet pipe 23. The two concentric pipes extend upward throughout the entire casings C and D. Inside the casing D the pipe has integral spiral fins F to absorb maximum heat. At the upper end of the two pipes a cap 24 closes the larger pipe. The smaller pipe 22 ends before it reaches the cap 24 so that the smaller pipe empties into the larger surrounding pipe 23 near the terminal cap 24. The cold water therefore passes upward through the smaller inner pipe and is drawn oif downward through the larger pipe by any desired valve connection.

In this modification also an extension of the larger pipe 23 contains a thermostat 25 at its hottest point and has an auxiliary draw-ofi pipe 23. Water drawn off through this auxiliary pipe will be at a high degree of temperature, as for example 180 degrees Fahrenheit, whereas it will be reduced to a lower temperature, as for example degrees, when drawn off at the bottom of the apparatus through the outer pipe 21.

Fig. 3 is a modification comprising a burner B positioned inside a cylindrical casing C. Wound spirally on the outside of the casing are co-axial inner pipe 32 and outer pipe 33. In this modification cold water is admitted through an extension 34 to the outer pipe 33 and passes upward therethrough in a spiral path to the top of the chamber and there forms a finned pancake coil 3? lying horizontally in the top of the casing. This fiat coil portion is provided with integral circular flanges F like those shown in the other figures of the drawing. After forming the fiat coil 31 the pipe 33 has a lateral extension 38 in which is positioned a thermostatic control element T, controlling fuel supply for purposes already described. Connected to this lateral extension 38 is a hot water draw-ofi pipe 39 having a valve 41!. Also connected to the lateral extension 38 through the T-union 36 is the upper end of the small inner pipe 32, which extends downward to the hot-water outlet extension 4| controlled by valve 42. In operation of this modifi cation cold water enters extension 34, passes upward through the larger pipe 33 which surrounds the smaller pipe 32, is heated by contact with the hot water in pipe 32, by conduction from casing C, and by the hot gas passing upward through the finned coil 37 at the to of the casing. The heated water then passes through extension 38 eitherto the draw-off pipe 39, which delivers the water at a temperature of approximately or if not drawn 01f in that way passes downward through pipe 32 to the outlet 4|, controlled by valve 42. In passing downward from the pipe 32 the hot water, after having passed through a sterilizing temperature is re-' duced in heat by the upwardly traveling 'cold water in pipe 33, and is discharged at a temperature suitable for ordinary uses, usually about 140.

Fig. 4 is a modification in which cold water enters through the pipe 52 and flows to a compartment 53, which is surrounded by a compartment 54, having a draw-off outlet 55 from which very hot water may be drawn. As the cold water passes through the compartment 53 it is partially heated by the surrounding hot water in compartment 54. The cold water passes upward from compartment 53 through pipe 56 to the top of a supplementary casing D and there connects through union 5'! with a downwardly spiralling helix 58 having integral heat transfer fins F. The lower end of this helix 58 empties into the larger compartment 54, carrying into it water that has been heated by the gases from burner B in its passage through the coil 58, and compartment 53. The hot water in compartment 54 tends to raise the temperature of the cold water in compartment 53, and vice versa, the cold water in compartment 53 reduces the temperature of the hot water in compartment 54 to" a usable temperature after it has been raised to sterilizing temperature in coil 58.

A draw-01f pipe 50 is connectedby T-union 6| to the lower end of helix 58, and is controlled by valve 62. This furnishes an outlet for supplying water at its hottest point.

It will be apparent that in each of the embodiments above described the cold water at certain stages is surrounded by water that has been heated to a sterilizing temperature, thereby reducing the sterile hot water to a desired temperature suitable for ordinary use. At one stage of its passage through each form of the device all of the water that passes through the device has been heated to a point that results in sterilization. That point is approximately 180. Consequently, even though the water may be brought out of the device at a lower temperature by regulating the thermostatic control and by suitable positioning and proportioning of the various parts, all of the water drawn off will have been sterilized by being raised to a high temperature even though delivered at a lower temperature more suitable for ordinary use without mixing with unsterilized cold water. There is no exposure to contamination in the cooling process, therefore completely sterile water is delivered though at a temperature below that required portion of the inlet pipe to provide heat exchange between water in said concentric pipes, the outlet pipe being connected at its upper end with the lower end of said secondary heat-absorbing coil.

7 2. Apparatus for heating and sterilizing water, comprising a combustion chamber, a coiled water outlet pipe inside the chamber, a smaller inlet pipe having a primary heat-exchange portion positioned inside said outlet pipe, and having a coiled secondary portion directly exposed to heat in the chamber, said secondary portion opening into the outlet pipe, the helix axis of the primary portion coinciding with the helix axis of the outlet pipe, and the outlet return pipe being in concentric enveloping relation with the said primary portion, whereby to expose discharging heated water to heat exchange with incoming cold water.

3. Apparatus for heating and sterilizing water comprising a combination chamber, a coiled outlet pipe inside the chamber, a coiled inlet pipe having a heat-exchange portion enveloped by said outlet pipe, a secondary coiled pipe positioned above the outlet pipe and exposed directly to heat in the combustion chamber, an open connection between the inlet coiled pipe and the secondary coiled pipe, the secondary heat absorbing coil being connected to the upper end of the outlet pipe, whereby to expose hot water being discharged after heating to the cooling effect of the incoming water and vice versa.

4. A device for heating and sterilizing water,

comprising a combustion chamber, an inlet pipe for passing cold water into the chamber, said inlet pipe having a primary heat-exchange portion extending upwardly through the chamber and coiledtherein, a secondary coiled portion in direct heat absorbing contact with the gases of combustion, and an outlet pipe connected to said secondary portion and adapted to carry the heated water to a discharge outlet, said outlet pipe surrounding and concentrically enveloping the primary portion of the said inlet pipe.

5. A device as set forth in claim 4, having a supplemental draw-off outlet positioned between the secondary coil and the outlet pipe and a valve controlling said supplemental outlet.

6. Apparatus for heating water to sterilizing temperature and thereafter reducing it to a lower temperature for use, comprising a combustion chamber, a water inlet pipe formed into an upwardly extending primary coil surrounding a portion of the combustion chamber, a downwardly wound secondary coil positioned in the combustion chamber above the primary coil and surrounding an upper portion of the combustion chamber in direct heat-absorbing position, an open connection between the said primary and secondary coils, an outlet return pipe connected to the discharge end of said secondary coil, the outlet return pipe forming a third coil arranged in enveloping concentric heat-exchange relation to the pipe of the primary coil, and an intermediate draw-ofi valve controlling an opening positioned near the discharge end of the secondary coil.

HARRISON D. STERICK.

REFERENCES CITED The following references are of record in the file of this patent:

UNITED STATES PATENTS Number Name Date 200,482 Salisbury Feb. 19, 1878 200,938 Salisbury Mar. 5, 1878 737,026 Ruby Aug. 25, 1903 1,646,560 Reinecke Oct. 25,1927 1,898,078 Cross Feb. 21, 1933 1,980,424 Morgan Nov. 13, 1934 2,008,528 I Warren July 16, 1935 FOREIGN PATENTS Number Country. Date 15,315 Great Britain June 30, 1911 

